Dynamic Anchor Subcarriers Selection for 802.11 CSI Compression With Optimal Piecewise Linear Interpolation

In next-generation Wi-Fi networks (IEEE 802.11be and beyond), the overhead of Channel State Information (CSI) feedback is a critical bottleneck for Multi-User MIMO (MU-MIMO) operation. The standard approach to compression uses subcarrier grouping, where channel parameters are fully transmitted only for uniformly spaced anchor subcarriers and interpolated for the rest. This uniform spacing is suboptimal for frequency-selective fading channels. This letter proposes a novel CSI compression algorithm that dynamically selects optimal anchor subcarriers for piecewise linear interpolation. The anchor selection problem is formulated as a shortest path problem and solved efficiently using dynamic programming. The proposed algorithm provides significant gains over the standard uniform placement, achieving up to 6 dB improvement in average Signal-to-Interference-plus-Noise Ratio for the same feedback overhead.